Provide password to `nmcli con up` in terminal 14.04

You can write-update a password to a seperate file. This works for me:

echo "vpn.secrets.password:MY_PASSWORD" > /my/vpn/password
nmcli con up uuid MY_UUID passwd-file /my/vpn/password

You can set the password using the following command:

nmcli con mod VPNID vpn.secrets "password=VPNPASS"

where VPNPASS is the VPN password.

In order for this to work, you have to enable the pasword storage option in NetworkManager, as shown in this picture:

I am using Ubuntu 16.04.